Note: The power probe is connected to the power amplifier and signal generator via a network cable.
▲ Figure 5: Principle diagram of the calibration arrangement

Figure 6: Calibration Layout Illustration

Test Arrangement: The tested components must be connected with harnesses in accordance with their actual installation status in the vehicle (such as positive and negative poles of the power supply, signal lines, and control lines), and the length and layout of the harnesses must meet the standard requirements (usually simulating the length during the installation of the whole vehicle) (Figure 7). If the components have shielding shells or grounding requirements, they must be connected according to the design specifications.

Figure 7: Test Arrangement - Substitution Method

1-1-DUT
2-Test Harness
3-Load Simulator
4-Monitoring System
5-Power Supply
6-Manual Network
7-Fiber Optic
8-High-Frequency Equipment
10-Injection Probe
11-Ground Plane
12-Low Relative Dielectric Constant Support (εr≤1.4)
13-Shielding Room
▲Figure 7: Test Arrangement - Closed-Loop Method

Test Parameters:

According to the test standards (such as ISO 11452-4) and the type of parts, set the parameters of the interference signal:

1.Frequency Range: 0.1MHz-400MHz, some manufacturers extend the test frequency band to 0.01MHz.

2.Test Step: Logarithmic and linear steps, as required by the actual test plan

3.Test Strength: Graded by current intensity (mA/dBuA), for example, Level 1 ~ Level 5, the higher the level, the more stringent the requirements, as required by the actual test; 

4.Modulation Method: Unmodulated sine wave and modulated sine wave with a 1kHz frequency and 80% amplitude modulation depth are used to simulate the interference characteristics of actual communication signals;

5.Dwell Time: Not less than 1s (to ensure that the tested parts can respond functionally)

6.Injection Method: As per the actual test plan, ISO 11452-4:2020 does not have DBCI testing, and the requirements of different automakers vary.

① Common Mode Injection (CBCI) (Figure 8): All the cables of the tested parts are clamped within the injection probe.

② Differential Mode Injection (DBCI) (Figure 9): All the cables of the tested parts except for the ground wire are clamped within the injection probe.

Figure 8 Common Mode Injection (CBCI)	Figure 9 Differential Bias Injection (DBCI)

7. Test Position: The actual test plan shall be followed. ISO 11452-4:2020 does not include DBCI testing, and the requirements of different vehicle manufacturers vary. ① Common Mode Injection (CBCI): The probe is 150mm, 450mm, and 750mm away from the connector of the tested component. ② Differential Mode Injection (DBCI): The probe is 150mm and 450mm away from the connector of the tested component.

Test Process Briefing:

1. Environment Setup: Arrange the DUT, cables, probes, and other equipment strictly according to the standard requirements on the test bench.

2. System Calibration: Remove the DUT, scan point by point within the test frequency range, adjust the power amplifier output, and make the current measured by the monitoring probe reach the target value. Record the required input power of the power amplifier. This document is called the 'Calibration Sheet'.

3. Test Execution: Connect the DUT, and the software automatically controls the power amplifier to output the corresponding power at each frequency point according to the 'Calibration Sheet'.

4. Function Monitoring: Continuously monitor all functions of the DUT throughout the scanning process, and record any degradation or failure phenomena (such as communication errors, signal deviation, reset, crash, etc.).

5. Result Judgment: Judge whether the DUT passes or fails based on the product standard (corporate standards are usually more stringent than international standards).

Section 3: Advantages and Limitations of BCI

Advantages:

- Non-invasive: No need to damage cables or alter the design of the Device Under Test (DUT), with good repeatability of the test.

- Efficient: Compared to the radiation immunity test in the electromagnetic wave anechoic chamber, the BCI test is faster and more cost-effective.

- Direct: Can accurately evaluate the coupling sensitivity of the cables.

Limitations:

- Mainly assesses conducted immunity, and the assessment of immunity to spatial radiation requires the combination of other methods (such as ISO 11452-2 Radiation Interference - ALSE).

Section 4: Summary

The high current injection immunity test is a 'must-pass' stage for automotive electronic components from design to mass production. Its core value lies in the early exposure of potential risks of components in complex electromagnetic environments through standardized interference simulation. For component manufacturers, paying attention to the testing phase and optimizing the immunity design is the key to enhancing product competitiveness.